Spectral diffusion and the Stark effect in colloidal quantum dots

Next BIU Engineering Colloquium,
Dr. Ron Tenne, Sunday, 14.1.24 @11:00, BIU Engineering Building 1103, Room 329

Via Zoom: https://uni-konstanz-de.zoom.us/j/97495106919
====================================

We are delighted to host

Dr. Ron Tenne

University of Konstanz, Germany

Dr. Tenne will give a talk on the subject:

Spectral diffusion and the Stark effect in colloidal quantum dots

Abstract: While colloidal quantum dots (CQDs) have become an important building block in electro-optical devices, in the realm of quantum science and technology, they are often considered inferior to other types of quantum emitters such as solid-state defects and epitaxial quantum dots. Despite their single-photon emission ^[1], demonstrations of quantum coherence and control are largely still lacking. The main obstacle towards these is spectral diffusion – stochastic fluctuations in the energy of photons emitted from an individual CQD even at cryogenic temperatures. In this talk, I will present our recent work providing, for the first time, direct and definitive proof that these fluctuations arise from stochastic electric fields in the micro environment ^[2]. The high sensitivity of CQDs to electric fields, through the quantum-confined Stark effect, is not only a bug but also a feature. I will present concepts for broadband coherent control of the temporal wavefunction of the emitted photon. Relying on tools from the terahertz and femtosecond-laser toolboxes ^[3,4], spectroscopy at fast-to-ultrafast (millisecond-to-femtosecond) timescales, will play a detrimental role in fulfilling the unique potential that CQDs hold in the field of quantum optics.

1. R. Tenne, U. Rossman, B. Rephael, Y. Israel, A. Krupinski-Ptaszek, R. Lapkiewicz, Y. Silberberg, and D. Oron, Super-Resolution Enhancement by Quantum Image Scanning Microscopy, Nature Photonics 13, 116 (2019).
2. F. Conradt, V. Bezold, V. Wiechert, S. Huber, S. Mecking, A. Leitenstorfer, and R. Tenne, Electric-Field Fluctuations as the Cause of Spectral Instabilities in Colloidal Quantum Dots, Nano Lett. 23, 9753 (2023).
3.  P. Henzler et al., Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot, Physical Review Letters 126, 067402 (2021).
4. P. Fischer, G. Fitzky, D. Bossini, A. Leitenstorfer, and R. Tenne, Quantitative Analysis of Free-Electron Dynamics in InSb by Terahertz Shockwave Spectroscopy, Physical Review B 106, 205201 (2022).

Short bio: Ron completed a BSc. in Materials Engineering and Physics at the Technion Institute of Technology, Israel in 2009. He continued for an MSc. and PhD. in Physics under the supervision of Prof. Dan Oron in the Physics Faculty at the Weizmann Institute, Israel. In Weizmann, he studied the quantum nature of the radiation from individual quantum dots and, in particular, how it can be applied to enhance microscopy and spectroscopy techniques. In 2020, he moved to the University of Konstanz in Germany working under the guidance of Prof. Alfred Leitenstorfer and sponsored by the Minerva Postdoctoral Fellowship. As a junior group leader in Konstanz, his research focused on understanding the sources of noise in the emission of quantum dots at low temperatures. In addition, he took part in several innovative projects concerning the generation and detection of light on an ultrafast timescale. Ron finished his BSc with a summa cum laude designation, was awarded the Feinberg graduate school dean’s award for his MSc work and the Israel Dostrovsky memorial award for his PhD thesis. As of 2023, he serves on the research council of the collaborative research center SFB 1432 centered at the University of Konstanz.